资源类型

期刊论文 1118

会议视频 11

年份

2023 76

2022 92

2021 75

2020 81

2019 58

2018 51

2017 54

2016 48

2015 54

2014 50

2013 43

2012 47

2011 38

2010 48

2009 55

2008 49

2007 40

2006 29

2005 27

2004 21

展开 ︾

关键词

数学模型 13

模型试验 9

数值模拟 8

模型 7

COVID-19 4

不确定性 4

GM(1 3

计算机模拟 3

1)模型 2

DX桩 2

D区 2

Preissmann格式 2

SARS 2

TRIZ 2

Weibull分布 2

k-ε模型 2

临震信号 2

云模型 2

人员疏散 2

展开 ︾

检索范围：

排序： 展示方式：

Microenvironmental time-activity patterns in Chongqing, China

Yu ZHAO, Shuxiao WANG, Gangcai CHEN, Fei WANG, Kristin AUNAN, Jiming HAO

《环境科学与工程前沿（英文）》 2009年 第3卷 第2期   页码 200-209 doi: 10.1007/s11783-009-0010-y

摘要： An investigation using recall questionnaires was conducted in winter and autumn 2006 to evaluate the time-activity patterns in Chongqing, China. The average time spent in seven microenvironments (MEs) including outdoors, transit, living room, bedroom, kitchen, classroom/office, and other indoors were found to be about 3.5, 1.1, 2.5, 9.7, 1.4, 4.2, and 1.7 h per day, respectively. According to the results of a nonparametric test, the sampling period and day of week were significant for the variation of the time spent in all MEs except for transit and outdoors. The time budget was analyzed using a general linear model (GLM), which exhibited significant variability by demographic factors such as gender, age, residence, education, and household income.

关键词： time-activity patterns     microenvironment     general linear model (GLM)     Chongqing     China    

HTML PDF 收藏

General expression for linear and nonlinear time series models

Ren HUANG, Feiyun XU, Ruwen CHEN

《机械工程前沿（英文）》 2009年 第4卷 第1期   页码 15-24 doi: 10.1007/s11465-009-0015-z

摘要： The typical time series models such as ARMA, AR, and MA are founded on the normality and stationarity of a system and expressed by a linear difference equation; therefore, they are strictly limited to the linear system. However, some nonlinear factors are within the practical system; thus, it is difficult to fit the model for real systems with the above models. This paper proposes a general expression for linear and nonlinear auto-regressive time series models (GNAR). With the gradient optimization method and modified AIC information criteria integrated with the prediction error, the parameter estimation and order determination are achieved. The model simulation and experiments show that the GNAR model can accurately approximate to the dynamic characteristics of the most nonlinear models applied in academics and engineering. The modeling and prediction accuracy of the GNAR model is superior to the classical time series models. The proposed GNAR model is flexible and effective.

关键词： linear and nonlinear     autoregressive model     system identification     time series analysis    

HTML PDF 收藏

Scaled boundary finite element method with exact defining curves for two-dimensional linear multi-field

Jaroon RUNGAMORNRAT, Chung Nguyen VAN

《结构与土木工程前沿（英文）》 2019年 第13卷 第1期   页码 201-214 doi: 10.1007/s11709-018-0488-0

摘要： This paper presents an efficient and accurate numerical technique based upon the scaled boundary finite element method for the analysis of two-dimensional, linear, second-order, boundary value problems with a domain completely described by a circular defining curve. The scaled boundary finite element formulation is established in a general framework allowing single-field and multi-field problems, bounded and unbounded bodies, distributed body source, and general boundary conditions to be treated in a unified fashion. The conventional polar coordinates together with a properly selected scaling center are utilized to achieve the exact description of the circular defining curve, exact geometry of the domain, and exact spatial differential operators. Standard finite element shape functions are employed in the discretization of both trial and test functions in the circumferential direction and the resulting eigenproblem is solved by a selected efficient algorithm. The computational performance of the implemented procedure is then fully investigated for various scenarios to demonstrate the accuracy in comparison with standard linear elements.

关键词： multi-field problems     defining curve     exact geometry     general boundary conditions     SBFEM    

HTML PDF 收藏

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

《环境科学与工程前沿（英文）》 2009年 第3卷 第3期   页码 320-324 doi: 10.1007/s11783-009-0030-7

摘要： The best-fit equations of linear and non-linear forms of the two widely used kinetic models, namely pseudo-first-order and pseudo-second-order equations, were compared in this study. The experimental kinetics of methylene blue adsorption on activated carbon was used for this research. Both the correlation coefficient () and the normalized standard deviation Δ(%) were employed as error analysis methods to determine the best-fitting equations. The results show that the non-linear forms of pseudo-first-order and pseudo-second-order models were more suitable than the linear forms for fitting the experimental data. The experimental kinetics may have been distorted by linearization of the linear kinetic equations, and thus, the non-linear forms of kinetic equations should be primarily used to obtain the adsorption parameters. In addition, the Δ(%) method for error analysis may be better to determine the best-fitting model in this case.

关键词： adsorption     pseudo-first order     pseudo-second order     kinetic model     linear method     non-linear method    

HTML PDF 收藏

Cutting CO emissions through demand side regulation: Implications from multi-regional input–output linearprogramming model

《工程管理前沿（英文）》   页码 452-461 doi: 10.1007/s42524-022-0209-1

摘要： This study combines multi-regional input–output (MRIO) model with linear programming (LP) model to explore economic structure adjustment strategies for the reduction of carbon dioxide (CO2) emissions. A particular feature of this study is the identification of the optimal regulation sequence of final products in various regions to reduce CO2 emissions with the minimum loss in gross domestic product (GDP). By using China’s MRIO tables 2017 with 28 regions and 42 economic sectors, results show that reduction in final demand leads to simultaneous reductions in GDP and CO2 emissions. Nevertheless, certain demand side regulation strategy can be adopted to lower CO2 emissions at the smallest loss of economic growth. Several key final products, such as metallurgy, nonmetal, metal, and chemical products, should first be regulated to reduce CO2 emissions at the minimum loss in GDP. Most of these key products concentrate in the coastal developed regions in China. The proposed MRIO–LP model considers the inter-relationship among various sectors and regions, and can aid policy makers in designing effective policy for industrial structure adjustment at the regional level to achieve the national environmental and economic targets.

关键词： CO2 emissions     demand side regulation     multi-regional input–output model     linear programming model    

HTML PDF 收藏

Model reduction techniques for dynamics analysis of ultra-precision linear stage

Xuedong CHEN, Zhixin LI

《机械工程前沿（英文）》 2009年 第4卷 第1期   页码 64-70 doi: 10.1007/s11465-009-0009-x

摘要： Spring-damping elements are used to simplify the internal interaction in the proposed finite element (FE) model of an ultra-precision linear stage. The dynamics behavior is studied. The comparison between mode shapes from the eigenvalue analysis shows that the components, except the translator, can represent system dynamics characteristics. A reduction approach is used to simplify the system in a dynamic studied. There is little difference between the vibration mode and the response analysis. The experimental modal analysis proves the validity of the reduction approach, which can be generalized to the development and dynamics characteristic study of a complex system model to obviously save computational resource.

关键词： dynamics analysis     air-bearing     linear stage     reduction    

HTML PDF 收藏

Linear and nonlinear elastic analysis of closely spaced strip foundations using Pasternak model

Priyanka GHOSH, S. RAJESH, J. SAI CHAND

《结构与土木工程前沿（英文）》 2017年 第11卷 第2期   页码 228-243 doi: 10.1007/s11709-016-0370-x

摘要： In this study, an attempt is made to determine the interaction effect of two closely spaced strip footings using Pasternak model. The study considers small strain problem and has been performed using linear as well as nonlinear elastic analysis to determine the interaction effect of two nearby strip footings. The hyperbolic stress-strain relationship has been considered for the nonlinear elastic analysis. The linear elastic analysis has been carried out by deriving the equations for the interference effect of the footings in the framework of Pasternak model equation; whereas, the nonlinear elastic analysis has been performed using the finite difference method to solve the second order nonlinear differential equation evolved from Pasternak model with proper boundary conditions. Results obtained from the linear and the nonlinear elastic analysis are presented in terms of non-dimensional interaction factors by varying different parameters like width of the foundation, load on the foundation and the depth of the rigid base. Results are suitably compared with the existing values in the literature.

关键词： bearing capacity     linear and non-linear elasticity     foundation     interaction effect     numerical modeling     Pasternak model    

HTML PDF 收藏

Design and modeling of a free-piston engine generator

《能源前沿（英文）》   页码 811-821 doi: 10.1007/s11708-022-0848-2

摘要： Free-piston engine generators (FPEGs) can be applied as decarbonized range extenders for electric vehicles because of their high thermal efficiency, low friction loss, and ultimate fuel flexibility. In this paper, a parameter-decoupling approach is proposed to model the design of an FPEG. The parameter-decoupling approach first divides the FPEG into three parts: a two-stroke engine, an integrated scavenging pump, and a linear permanent magnet synchronous machine (LPMSM). Then, each of these is designed according to predefined specifications and performance targets. Using this decoupling approach, a numerical model of the FPEG, including the three aforementioned parts, was developed. Empirical equations were adopted to design the engine and scavenging pump, while special considerations were applied for the LPMSM. A finite element model with a multi-objective genetic algorithm was adopted for its design. The finite element model results were fed back to the numerical model to update the LPMSM with increased fidelity. The designed FPEG produced 10.2 kW of electric power with an overall system efficiency of 38.5% in a stable manner. The model provides a solid foundation for the manufacturing of related FPEG prototypes.

关键词： free-piston engine generator     linear permanent magnet synchronous machine     system design     numerical model     finite element method    

HTML PDF 收藏

基于正定约束广义秩信号模型的低复杂度稳健自适应算法 Article

Yu-tang ZHU,Yong-bo ZHAO,Jun LIU,Peng-lang SHUI

《信息与电子工程前沿（英文）》 2016年 第17卷 第11期   页码 1245-1252 doi: 10.1631/FITEE.1601112

摘要： 本文针对广义秩信号模型提出一种低复杂度的稳健自适应波束形成算法，用来抑制期望信号的阵列响应失配和接收信号的协方差矩阵失配。该波束形成算法不仅考虑期望信号以及接收信号协方差矩阵不确定集的范数有界性，还保证期望信号协方差矩阵的正定性。最终，本文在最差性能优化准则下推出一个计算简单的闭式加权矢量。计算机仿真结果验证了所提波束形成算法的有效性和稳健性。

关键词： 波束形成；广义秩；低复杂度；正定约束；模型失配    

HTML PDF 收藏

Creep and recovery behaviors of magnetorheological elastomers

Weihua LI, Yang ZHOU, Tongfei TIAN, Gursel ALICI,

《机械工程前沿（英文）》 2010年 第5卷 第3期   页码 341-346 doi: 10.1007/s11465-010-0096-8

摘要： This paper presents experimental and modeling study of creep and recovery behaviors of magneto-rheological elastomers (MREs) under constant stresses. Experimental study was accomplished using a rheometer with parallel-plate geometry. Under constant stresses ranging from a small value to a large one, the resultant strains were recorded. The experimental results demonstrated that MREs behave as linear visocleastic properties. The effects of the magnetic field and stress on MRE creep behaviors were discussed. Moreover, a four-parameter viscoelastic model was developed to describe MRE creep behaviors. The comparison between the experimental results and the modeling predictions indicates that the model can predict MRE creep behaviors very well.

关键词： magneto-rheological elastomers (MREs)     creep     recovery     linear viscoelastic model    

HTML PDF 收藏

Design and analysis of linear oscillating motor for linear pump application-magnetic field, dynamics

Zongxia JIAO,Tianyi WANG,Liang YAN

《机械工程前沿（英文）》 2016年 第11卷 第4期   页码 351-362 doi: 10.1007/s11465-016-0407-9

摘要：

A linear oscillating motor is an electromagnetic actuator that can achieve short-stroke reciprocating movement directly without auxiliary transmission mechanisms. It has been widely used in linear pump applications as the source of power and motion. However, because of the demand of high power density in a linear actuation system, the performance of linear oscillating motors has been the focus of studies and deserves further research for high power density. In this paper, a general framework of linear oscillating motor design and optimization is addressed in detail, including the electromagnetic, dynamics, and thermal aspects. First, the electromagnetic and dynamics characteristics are modeled to reveal the principle for optimization. Then, optimization and analysis on magnetic structure, resonant system, and thermal features are conducted, which provide the foundation for prototype development. Finally, experimental results are provided for validation. As a whole, this process offers complete guidance for high power density linear oscillating motors in linear pump applications.

关键词： linear oscillating motor     linear pump     magnetic field     motor optimization    

HTML PDF 收藏

A novel intravenous general anesthetic--- emulsified isoflurane: from bench to bedside

null

《医学前沿（英文）》 2012年 第6卷 第4期   页码 381-387 doi: 10.1007/s11684-012-0229-z

摘要：

Application of volatile anesthetics greatly alters modern medicine. There are obvious advantages of volatile anesthetics such as strong anesthetic potency, rapid onset and elimination through respiration system. Isoflurane is one of the most widely used volatile anesthetics in clinic. Emulsified isoflurane, the emulsion of isoflurane, is a novel intravenous general anesthetic. With the development of emulsified isoflurane in the past fifteen years, its utility has spread from intravenous general anesthesia to various fields including regional anesthesia, organ protection, as well as anesthetic pharmacological study. In this review, we will summarize literatures of emulsified isoflurane about its history, clinical application and future potential utility in the above mentioned fields.

关键词： emulsified isoflurane (EI)     general anesthesia     regional anesthesia     organ protection     anesthetic pharmacological study    

HTML PDF 收藏

有限资源下最大可靠性网络流中断模型

赵 佳,于 华

《中国工程科学》 2015年 第17卷 第1期   页码 137-142

摘要：

提出了最大可靠性网络流中断模型。此模型是在给定的网络图中，通过在边上设置监测点来阻止给定两个顶点之间的网络流量，同时考虑所设置监测点失效的可能，在给定的资源限制下，最大化中断网络流的可能性，即给定起点和终点的网络图，在资源有限的情况下，选择一些边设置监测点使得从起点到终点的所有路都包含尽可能多的已被设置中断点的边。在给定图中，两点之间的路的条数是图的规模的指数次幂，为此将此模型转化为双层整数规划模型，鉴于双层整数规划模型在一般情况下是不可解的，通过探讨下层整数规划问题与其线性规划松弛之间的关系以及线性规划对偶理论来解此双层整数规划模型。本文不仅将该模型约束的个数从图的规模的指数次幂降到一次幂，同时也提供了一种解双层整数规划问题的方法。

关键词： 中断模型；k-可靠性；对偶；线性规划松弛；互补松弛型    

HTML PDF 收藏

Numerical investigation of circle defining curve for two-dimensional problem with general boundaries

Chung Nguyen VAN

《结构与土木工程前沿（英文）》 2019年 第13卷 第1期   页码 92-102 doi: 10.1007/s11709-018-0472-8

摘要： The scaled boundary finite element method (SBFEM) is applied to the static analysis of two dimensional elasticity problem, boundary value problems domain with the domain completely described by a circular defining curve. The scaled boundary finite element equations is formulated within a general framework integrating the influence of the distributed body force, general boundary conditions, and bounded and unbounded domain. This paper investigates the possibility of using exact geometry to form the exact description of the circular defining curve and the standard finite element shape function to approximate the defining curve. Three linear elasticity problems are presented to verify the proposed method with the analytical solution. Numerical examples show the accuracy and efficiency of the proposed method, and the performance is found to be better than using standard linear element for the approximation defining curve on the scaled boundary method.

关键词： exact geometry     circular defining curve     general boundaries     SBFEM    

HTML PDF 收藏

Microdamage study of granite under thermomechanical coupling based on the particle flow code

《结构与土木工程前沿（英文）》   页码 1413-1427 doi: 10.1007/s11709-023-0953-2

摘要： The thermomechanical coupling of rocks refers to the interaction between the mechanical and thermodynamic behaviors of rocks induced by temperature changes. The study of this coupling interaction is essential for understanding the mechanical and thermodynamic properties of the surrounding rocks in underground engineering. In this study, an improved temperature-dependent linear parallel bond model is introduced under the framework of a particle flow simulation. A series of numerical thermomechanical coupling tests are then conducted to calibrate the micro-parameters of the proposed model by considering the mechanical behavior of the rock under different thermomechanical loadings. Good agreement between the numerical results and experimental data are obtained, particularly in terms of the compression, tension, and elastic responses of granite. With this improved model, the thermodynamic response and underlying cracking behavior of a deep-buried tunnel under different thermal loading conditions are investigated and discussed in detail.

关键词： thermomechanical coupling effect     granite     improved linear parallel bond model     thermal property     particle flow code    

HTML PDF 收藏

标题 作者 时间 类型 操作

Microenvironmental time-activity patterns in Chongqing, China

Yu ZHAO, Shuxiao WANG, Gangcai CHEN, Fei WANG, Kristin AUNAN, Jiming HAO

期刊论文

General expression for linear and nonlinear time series models

Ren HUANG, Feiyun XU, Ruwen CHEN

期刊论文

Scaled boundary finite element method with exact defining curves for two-dimensional linear multi-field

Jaroon RUNGAMORNRAT, Chung Nguyen VAN

期刊论文

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

期刊论文

Cutting CO emissions through demand side regulation: Implications from multi-regional input–output linearprogramming model

期刊论文

Model reduction techniques for dynamics analysis of ultra-precision linear stage

Xuedong CHEN, Zhixin LI

期刊论文

Linear and nonlinear elastic analysis of closely spaced strip foundations using Pasternak model

Priyanka GHOSH, S. RAJESH, J. SAI CHAND

期刊论文

Design and modeling of a free-piston engine generator

期刊论文

基于正定约束广义秩信号模型的低复杂度稳健自适应算法

Yu-tang ZHU,Yong-bo ZHAO,Jun LIU,Peng-lang SHUI

期刊论文

Creep and recovery behaviors of magnetorheological elastomers

Weihua LI, Yang ZHOU, Tongfei TIAN, Gursel ALICI,

期刊论文

Design and analysis of linear oscillating motor for linear pump application-magnetic field, dynamics

Zongxia JIAO,Tianyi WANG,Liang YAN

期刊论文

A novel intravenous general anesthetic--- emulsified isoflurane: from bench to bedside

null

期刊论文

有限资源下最大可靠性网络流中断模型

赵 佳,于 华

期刊论文

Numerical investigation of circle defining curve for two-dimensional problem with general boundaries

Chung Nguyen VAN

期刊论文

Microdamage study of granite under thermomechanical coupling based on the particle flow code

期刊论文